The cruise ship industry and Carnival Cruise lines in particular, are in the news again a little more than a year after Carnival’s Costa Concordia ran aground leaving 32 dead.

Lt. Cmdr. Teresa Hatfield, head of the U.S. Coast Guard Marine Casualty Investigation Team, said the cause of the Carnival Triumph fire was oil from a diesel fuel line that caught fire when it made contact with a hot surface.

Since this cruise ship is registered in the Bahamas, the Bahamas Maritime Authority investigation will lead. Cruise ship companies register their ships in other countries in order to avoid the employment and safety regulations that US registration would require. Only if they operate solely within the United States, are passenger ships required to have US registration.

SS Carnival Triumph was left without power and propulsion following an engine room fire on 10 February. Photo via boards.cruisecritic.com

The National Traffic Safety Board (NTSB) investigates mishaps aboard US flagged vessels. Since 2000 there have been 9 NTSB investigations of fires aboard US flagged passenger vessels. These were ferries or riverboat cruise ships operating within the United States. One of the fires was caused by a passenger’s prohibited personal electric water heater that shorted out. The remaining 8 fires all occurred in the engine room.

Engine room fires are generally of 2 types: oil or electric. Modern engine rooms have diesel fuel oil, lubricating oil, and hydraulic oil under pressure distributed throughout the engine room. In a typical oil fire, there are two faults. First, the pipe or hose carrying the oil leaks. These oils combust at between 450-500F. The component most likely to ignite them is the engine exhaust piping which can run as hot as 800F. They could also be ignited by a spark from an electrical component like a breaker or a generator.

Since the engine exhaust piping is insulated, you need two faults. First, a break in the pipe and secondly a gap in the insulation. The oil leaks out the break and makes it through the gap and ignites. These are things that trained crews will inspect for, find, and repair. 5 of the 8 fires investigated by the NTSB were caused by igniting oil.

It is important to note that just as your car’s engine compartment doesn’t spontaneously and without warning catch fire, the same is true in the large engine rooms of today’s cruise ships. There are always precursors to the event. For the oil line, such precursors could be leaks that are unattended to, poor maintenance practices when reconnecting piping, or not getting hoses inspected and replaced on a regular schedule. For the “hot surface,” precursors could be gaps in insulation, or sparking on generator or breaker components that isn’t seen or repaired.

The remaining three fires were electrical.

Electrical fires can result from shorts caused by breakdowns in insulation, high resistance connections where electricity is supposed to flow which causes heat build up, or poor housekeeping, maintenance and inspection processes on switchboards and breakers. Sometimes the fault is a manufacturing or maintenance defect that occurred months or years prior to the fire but there are typically indicators that something is amiss. Better crews pay attention to these indicators and act on them. Poorer crews miss the indicators, or when they see them, fail to correct the underlying cause.

Two weeks prior the fire, this ship Carnival Triumph suffered a 5-hour delay returning to port when a fire broke out in the engine room. The report cited a short in a connection box forward of a generator. The Carnival Triumph’s US certifications are here.

Why would the entire ship end up without power and propulsion?

The official investigation has not identified the reason for this. In the NTSB investigations, fires in engines resulted in ships without propulsion but the electrical systems generally remained intact. Fires that took out the ship’s electrical generating and distribution system resulted in both a loss of electrical power and loss of propulsion power because the fuel oil and lubricating pumps and exhaust blowers needed to run the engines are electrically powered (or sometimes powered directly off the engine by a secondary shaft).

Cruise ships sure seem fragile. It is true that many cruises go off without a hitch but when problem occur failures seem to be catastrophic. A fire in one engine room of a modern ship would not cause complete failure of electrical and propulsion power without cascading failures.

Submarines and warships have long known how to create resilient systems where single failures do not incapacitate the entire vessel. As cruise ships expand in size and complexity, they would be wise to implement those systems.

The issue is one of leadership. The industry is run on a philosophy of compliance. The cruise ship operators have no incentive to build ships that are reliable, resilient. Instead they do the minimum to comply with government regulations. Further, they seek to register their vessels with governments that minimize the burden of compliance. This is the same mindset that resulted in the Titanic sailing with lifeboat capacity for only half the passengers.

One of the problems with Titanic was that cruise ships had undergone a period of dramatic increase in size over the previous 2 decades and regulations hadn’t kept up. A similar “growth spurt” and complexity spurt today has resulted in the modern design, complexity and construction of cruise ships outpacing the regulators.